This invention relates to a corrosion inhibiting composition and method and more particularly, to the use of a polyoxyalkylene amine for such inhibition.
Aqueous systems have been preferred for many applications which are subject to high heat or sparks. Such applications included hydraulic fluids for use in systems involving a high risk of fire, and quenchants used to cool heated metals during various metal working processes where the hot metals can ignite hydrocarbon based quenchants. However aqueous systems are corrosive towards metal particularly ferrous metals. One type of aqueous system presently in use comprises water, an alkylene and/or a polyoxyalkylene glycol and one or more other additives to impart corrosion inhibition to the system. Such aqueous systems can be used as quenching mediums for heat treating metal and for hydraulic fluids.
In a previously used aqueous system, which is noncorroding to metals, an inorganic nitrite, such as sodium nitrite, was used to impart improved corrosion inhibition to the aqueous alkylene glycol system. However, nitrites are somewhat toxic and in recent years there is a movement towards the removal of nitrites and their replacement with other materials to impart corrosion inhibition to the aqueous system.
A further problem with the previously used aqueous systems is their tendency to foam on the introduction of air or other gases into the system and the lack of corrosion inhibition in the air or gas space above the aqueous systems which is subject to corrosion.
U.S. Pat. No. 3,928,219 sets forth the use of lubricating oil compositions containing tetrapoly(oxyethylene) poly(oxypropylene) derivatives of ethylene diamine having molecular weights in the range from about 1650 to 15,000. The patent states that these lubricating oil compositions exhibit improved rust inhibition properties as well as sludge elimination.
U.S. Pat. No. 3,235,501 sets forth the inhibition of foaming in oil compositions containing materials which normally tend to promote foaming of the composition. The additives comprise a small amount of a polyalkyl oxylated aliphatic amine.
In an article by E. Ludosan et al in Rev. Coroz. 1972, 2(1), 39-44 (Rom), Chemical Abstracts 19315p (1973), the use of poly(ethoxyamines) is set forth as inhibiting the corrosion of steel in HCl or H.sub.2 SO.sub.4 solutions.
I. A. Mamedov et al in Azerb. Khim. Zh. 1977, (6), 49-50 (Russ), Chemicals Abstracts 89: 63203b (1978) sets forth the corrosion inhibition of steel by polyoxyethyleneamines under conditions encountered by steel equipment in crude oil extractions. The use of these amines broadened the range of corrosion inhibitors for steel in the electrolyte-hydrocarbon systems.
U.S. Pat. No. 3,235,501 sets forth the use of other amines containing a hydrophobic group of at least six carbon atoms.